/* eslint-disable prefer-rest-params */
/* eslint-disable default-case */
/* eslint-disable unicorn/consistent-function-scoping */
/* eslint-disable no-console */
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

'use strict';

(() => {
    const enosys = () => {
        const err = new Error('not implemented');
        err.code = 'ENOSYS';
        return err;
    };

    if (!globalThis.fs) {
        let outputBuf = '';
        globalThis.fs = {
            constants: { O_WRONLY: -1, O_RDWR: -1, O_CREAT: -1, O_TRUNC: -1, O_APPEND: -1, O_EXCL: -1, O_DIRECTORY: -1 }, // unused
            writeSync(fd, buf) {
                outputBuf += decoder.decode(buf);
                const nl = outputBuf.lastIndexOf('\n');
                if (nl !== -1) {
                    console.log(outputBuf.slice(0, nl));
                    outputBuf = outputBuf.slice(nl + 1);
                }
                return buf.length;
            },
            write(fd, buf, offset, length, position, callback) {
                if (offset !== 0 || length !== buf.length || position !== null) {
                    callback(enosys());
                    return;
                }
                const n = this.writeSync(fd, buf);
                callback(null, n);
            },
            chmod(path, mode, callback) {
                callback(enosys());
            },
            chown(path, uid, gid, callback) {
                callback(enosys());
            },
            close(fd, callback) {
                callback(enosys());
            },
            fchmod(fd, mode, callback) {
                callback(enosys());
            },
            fchown(fd, uid, gid, callback) {
                callback(enosys());
            },
            fstat(fd, callback) {
                callback(enosys());
            },
            fsync(fd, callback) {
                callback(null);
            },
            ftruncate(fd, length, callback) {
                callback(enosys());
            },
            lchown(path, uid, gid, callback) {
                callback(enosys());
            },
            link(path, link, callback) {
                callback(enosys());
            },
            lstat(path, callback) {
                callback(enosys());
            },
            mkdir(path, perm, callback) {
                callback(enosys());
            },
            open(path, flags, mode, callback) {
                callback(enosys());
            },
            read(fd, buffer, offset, length, position, callback) {
                callback(enosys());
            },
            readdir(path, callback) {
                callback(enosys());
            },
            readlink(path, callback) {
                callback(enosys());
            },
            rename(from, to, callback) {
                callback(enosys());
            },
            rmdir(path, callback) {
                callback(enosys());
            },
            stat(path, callback) {
                callback(enosys());
            },
            symlink(path, link, callback) {
                callback(enosys());
            },
            truncate(path, length, callback) {
                callback(enosys());
            },
            unlink(path, callback) {
                callback(enosys());
            },
            utimes(path, atime, mtime, callback) {
                callback(enosys());
            },
        };
    }

    if (!globalThis.process) {
        globalThis.process = {
            getuid() {
                return -1;
            },
            getgid() {
                return -1;
            },
            geteuid() {
                return -1;
            },
            getegid() {
                return -1;
            },
            getgroups() {
                throw enosys();
            },
            pid: -1,
            ppid: -1,
            umask() {
                throw enosys();
            },
            cwd() {
                throw enosys();
            },
            chdir() {
                throw enosys();
            },
        };
    }

    if (!globalThis.path) {
        globalThis.path = {
            resolve(...pathSegments) {
                return pathSegments.join('/');
            },
        };
    }

    // eslint-disable-next-line n/no-unsupported-features/node-builtins
    if (!globalThis.crypto) {
        throw new Error('globalThis.crypto is not available, polyfill required (crypto.getRandomValues only)');
    }

    if (!globalThis.performance) {
        throw new Error('globalThis.performance is not available, polyfill required (performance.now only)');
    }

    if (!globalThis.TextEncoder) {
        throw new Error('globalThis.TextEncoder is not available, polyfill required');
    }

    if (!globalThis.TextDecoder) {
        throw new Error('globalThis.TextDecoder is not available, polyfill required');
    }

    const encoder = new TextEncoder('utf-8');
    const decoder = new TextDecoder('utf-8');

    globalThis.Go = class {
        constructor() {
            this.argv = ['js'];
            this.env = {};
            this.exit = (code) => {
                if (code !== 0) {
                    console.warn('exit code:', code);
                }
            };
            this._exitPromise = new Promise((resolve) => {
                this._resolveExitPromise = resolve;
            });
            this._pendingEvent = null;
            this._scheduledTimeouts = new Map();
            this._nextCallbackTimeoutID = 1;

            const setInt64 = (addr, v) => {
                this.mem.setUint32(addr + 0, v, true);
                this.mem.setUint32(addr + 4, Math.floor(v / 4_294_967_296), true);
            };

            const getInt64 = (addr) => {
                const low = this.mem.getUint32(addr + 0, true);
                const high = this.mem.getInt32(addr + 4, true);
                return low + high * 4_294_967_296;
            };

            const loadValue = (addr) => {
                const f = this.mem.getFloat64(addr, true);
                if (f === 0) {
                    return;
                }
                if (!Number.isNaN(f)) {
                    return f;
                }

                const id = this.mem.getUint32(addr, true);
                return this._values[id];
            };

            const storeValue = (addr, v) => {
                const nanHead = 0x7F_F8_00_00;

                if (typeof v === 'number' && v !== 0) {
                    if (Number.isNaN(v)) {
                        this.mem.setUint32(addr + 4, nanHead, true);
                        this.mem.setUint32(addr, 0, true);
                        return;
                    }
                    this.mem.setFloat64(addr, v, true);
                    return;
                }

                if (v === undefined) {
                    this.mem.setFloat64(addr, 0, true);
                    return;
                }

                let id = this._ids.get(v);
                if (id === undefined) {
                    id = this._idPool.pop();
                    if (id === undefined) {
                        id = this._values.length;
                    }
                    this._values[id] = v;
                    this._goRefCounts[id] = 0;
                    this._ids.set(v, id);
                }
                this._goRefCounts[id]++;
                let typeFlag = 0;
                switch (typeof v) {
                    case 'object':
                        if (v !== null) {
                            typeFlag = 1;
                        }
                        break;
                    case 'string':
                        typeFlag = 2;
                        break;
                    case 'symbol':
                        typeFlag = 3;
                        break;
                    case 'function':
                        typeFlag = 4;
                        break;
                }
                this.mem.setUint32(addr + 4, nanHead | typeFlag, true);
                this.mem.setUint32(addr, id, true);
            };

            const loadSlice = (addr) => {
                const array = getInt64(addr + 0);
                const len = getInt64(addr + 8);
                return new Uint8Array(this._inst.exports.mem.buffer, array, len);
            };

            const loadSliceOfValues = (addr) => {
                const array = getInt64(addr + 0);
                const len = getInt64(addr + 8);
                const a = Array.from({ length: len });
                for (let i = 0; i < len; i++) {
                    a[i] = loadValue(array + i * 8);
                }
                return a;
            };

            const loadString = (addr) => {
                const saddr = getInt64(addr + 0);
                const len = getInt64(addr + 8);
                return decoder.decode(new DataView(this._inst.exports.mem.buffer, saddr, len));
            };

            const testCallExport = (a, b) => {
                this._inst.exports.testExport0();
                return this._inst.exports.testExport(a, b);
            };

            const timeOrigin = Date.now() - performance.now();
            this.importObject = {
                _gotest: {
                    add: (a, b) => a + b,
                    callExport: testCallExport,
                },
                gojs: {
                    // Go's SP does not change as long as no Go code is running. Some operations (e.g. calls, getters and setters)
                    // may synchronously trigger a Go event handler. This makes Go code get executed in the middle of the imported
                    // function. A goroutine can switch to a new stack if the current stack is too small (see morestack function).
                    // This changes the SP, thus we have to update the SP used by the imported function.

                    // func wasmExit(code int32)
                    'runtime.wasmExit': (sp) => {
                        sp >>>= 0;
                        const code = this.mem.getInt32(sp + 8, true);
                        this.exited = true;
                        delete this._inst;
                        delete this._values;
                        delete this._goRefCounts;
                        delete this._ids;
                        delete this._idPool;
                        this.exit(code);
                    },

                    // func wasmWrite(fd uintptr, p unsafe.Pointer, n int32)
                    'runtime.wasmWrite': (sp) => {
                        sp >>>= 0;
                        const fd = getInt64(sp + 8);
                        const p = getInt64(sp + 16);
                        const n = this.mem.getInt32(sp + 24, true);
                        globalThis.fs.writeSync(fd, new Uint8Array(this._inst.exports.mem.buffer, p, n));
                    },

                    // func resetMemoryDataView()
                    'runtime.resetMemoryDataView': (sp) => {
                        // eslint-disable-next-line @typescript-eslint/no-unused-vars
                        sp >>>= 0;
                        this.mem = new DataView(this._inst.exports.mem.buffer);
                    },

                    // func nanotime1() int64
                    'runtime.nanotime1': (sp) => {
                        sp >>>= 0;
                        setInt64(sp + 8, (timeOrigin + performance.now()) * 1_000_000);
                    },

                    // func walltime() (sec int64, nsec int32)
                    'runtime.walltime': (sp) => {
                        sp >>>= 0;
                        const msec = Date.now();
                        setInt64(sp + 8, msec / 1000);
                        this.mem.setInt32(sp + 16, (msec % 1000) * 1_000_000, true);
                    },

                    // func scheduleTimeoutEvent(delay int64) int32
                    'runtime.scheduleTimeoutEvent': (sp) => {
                        sp >>>= 0;
                        const id = this._nextCallbackTimeoutID;
                        this._nextCallbackTimeoutID++;
                        this._scheduledTimeouts.set(
                            id,
                            setTimeout(
                                () => {
                                    this._resume();
                                    while (this._scheduledTimeouts.has(id)) {
                                        // for some reason Go failed to register the timeout event, log and try again
                                        // (temporary workaround for https://github.com/golang/go/issues/28975)
                                        console.warn('scheduleTimeoutEvent: missed timeout event');
                                        this._resume();
                                    }
                                },
                                getInt64(sp + 8)
                            )
                        );
                        this.mem.setInt32(sp + 16, id, true);
                    },

                    // func clearTimeoutEvent(id int32)
                    'runtime.clearTimeoutEvent': (sp) => {
                        sp >>>= 0;
                        const id = this.mem.getInt32(sp + 8, true);
                        clearTimeout(this._scheduledTimeouts.get(id));
                        this._scheduledTimeouts.delete(id);
                    },

                    // func getRandomData(r []byte)
                    'runtime.getRandomData': (sp) => {
                        sp >>>= 0;
                        // eslint-disable-next-line n/no-unsupported-features/node-builtins
                        crypto.getRandomValues(loadSlice(sp + 8));
                    },

                    // func finalizeRef(v ref)
                    'syscall/js.finalizeRef': (sp) => {
                        sp >>>= 0;
                        const id = this.mem.getUint32(sp + 8, true);
                        this._goRefCounts[id]--;
                        if (this._goRefCounts[id] === 0) {
                            const v = this._values[id];
                            this._values[id] = null;
                            this._ids.delete(v);
                            this._idPool.push(id);
                        }
                    },

                    // func stringVal(value string) ref
                    'syscall/js.stringVal': (sp) => {
                        sp >>>= 0;
                        storeValue(sp + 24, loadString(sp + 8));
                    },

                    // func valueGet(v ref, p string) ref
                    'syscall/js.valueGet': (sp) => {
                        sp >>>= 0;
                        const result = Reflect.get(loadValue(sp + 8), loadString(sp + 16));
                        sp = this._inst.exports.getsp() >>> 0; // see comment above
                        storeValue(sp + 32, result);
                    },

                    // func valueSet(v ref, p string, x ref)
                    'syscall/js.valueSet': (sp) => {
                        sp >>>= 0;
                        Reflect.set(loadValue(sp + 8), loadString(sp + 16), loadValue(sp + 32));
                    },

                    // func valueDelete(v ref, p string)
                    'syscall/js.valueDelete': (sp) => {
                        sp >>>= 0;
                        Reflect.deleteProperty(loadValue(sp + 8), loadString(sp + 16));
                    },

                    // func valueIndex(v ref, i int) ref
                    'syscall/js.valueIndex': (sp) => {
                        sp >>>= 0;
                        storeValue(sp + 24, Reflect.get(loadValue(sp + 8), getInt64(sp + 16)));
                    },

                    // valueSetIndex(v ref, i int, x ref)
                    'syscall/js.valueSetIndex': (sp) => {
                        sp >>>= 0;
                        Reflect.set(loadValue(sp + 8), getInt64(sp + 16), loadValue(sp + 24));
                    },

                    // func valueCall(v ref, m string, args []ref) (ref, bool)
                    'syscall/js.valueCall': (sp) => {
                        sp >>>= 0;
                        try {
                            const v = loadValue(sp + 8);
                            const m = Reflect.get(v, loadString(sp + 16));
                            const args = loadSliceOfValues(sp + 32);
                            const result = Reflect.apply(m, v, args);
                            sp = this._inst.exports.getsp() >>> 0; // see comment above
                            storeValue(sp + 56, result);
                            this.mem.setUint8(sp + 64, 1);
                        } catch (error) {
                            sp = this._inst.exports.getsp() >>> 0; // see comment above
                            storeValue(sp + 56, error);
                            this.mem.setUint8(sp + 64, 0);
                        }
                    },

                    // func valueInvoke(v ref, args []ref) (ref, bool)
                    'syscall/js.valueInvoke': (sp) => {
                        sp >>>= 0;
                        try {
                            const v = loadValue(sp + 8);
                            const args = loadSliceOfValues(sp + 16);
                            const result = Reflect.apply(v, undefined, args);
                            sp = this._inst.exports.getsp() >>> 0; // see comment above
                            storeValue(sp + 40, result);
                            this.mem.setUint8(sp + 48, 1);
                        } catch (error) {
                            sp = this._inst.exports.getsp() >>> 0; // see comment above
                            storeValue(sp + 40, error);
                            this.mem.setUint8(sp + 48, 0);
                        }
                    },

                    // func valueNew(v ref, args []ref) (ref, bool)
                    'syscall/js.valueNew': (sp) => {
                        sp >>>= 0;
                        try {
                            const v = loadValue(sp + 8);
                            const args = loadSliceOfValues(sp + 16);
                            const result = Reflect.construct(v, args);
                            sp = this._inst.exports.getsp() >>> 0; // see comment above
                            storeValue(sp + 40, result);
                            this.mem.setUint8(sp + 48, 1);
                        } catch (error) {
                            sp = this._inst.exports.getsp() >>> 0; // see comment above
                            storeValue(sp + 40, error);
                            this.mem.setUint8(sp + 48, 0);
                        }
                    },

                    // func valueLength(v ref) int
                    'syscall/js.valueLength': (sp) => {
                        sp >>>= 0;
                        setInt64(sp + 16, Number.parseInt(loadValue(sp + 8).length));
                    },

                    // valuePrepareString(v ref) (ref, int)
                    'syscall/js.valuePrepareString': (sp) => {
                        sp >>>= 0;
                        const str = encoder.encode(String(loadValue(sp + 8)));
                        storeValue(sp + 16, str);
                        setInt64(sp + 24, str.length);
                    },

                    // valueLoadString(v ref, b []byte)
                    'syscall/js.valueLoadString': (sp) => {
                        sp >>>= 0;
                        const str = loadValue(sp + 8);
                        loadSlice(sp + 16).set(str);
                    },

                    // func valueInstanceOf(v ref, t ref) bool
                    'syscall/js.valueInstanceOf': (sp) => {
                        sp >>>= 0;
                        this.mem.setUint8(sp + 24, loadValue(sp + 8) instanceof loadValue(sp + 16) ? 1 : 0);
                    },

                    // func copyBytesToGo(dst []byte, src ref) (int, bool)
                    'syscall/js.copyBytesToGo': (sp) => {
                        sp >>>= 0;
                        const dst = loadSlice(sp + 8);
                        const src = loadValue(sp + 32);
                        if (!(src instanceof Uint8Array || src instanceof Uint8ClampedArray)) {
                            this.mem.setUint8(sp + 48, 0);
                            return;
                        }
                        const toCopy = src.subarray(0, dst.length);
                        dst.set(toCopy);
                        setInt64(sp + 40, toCopy.length);
                        this.mem.setUint8(sp + 48, 1);
                    },

                    // func copyBytesToJS(dst ref, src []byte) (int, bool)
                    'syscall/js.copyBytesToJS': (sp) => {
                        sp >>>= 0;
                        const dst = loadValue(sp + 8);
                        const src = loadSlice(sp + 16);
                        if (!(dst instanceof Uint8Array || dst instanceof Uint8ClampedArray)) {
                            this.mem.setUint8(sp + 48, 0);
                            return;
                        }
                        const toCopy = src.subarray(0, dst.length);
                        dst.set(toCopy);
                        setInt64(sp + 40, toCopy.length);
                        this.mem.setUint8(sp + 48, 1);
                    },

                    debug: (value) => {
                        console.log(value);
                    },
                },
            };
        }

        async run(instance) {
            if (!(instance instanceof WebAssembly.Instance)) {
                throw new TypeError('Go.run: WebAssembly.Instance expected');
            }
            this._inst = instance;
            this.mem = new DataView(this._inst.exports.mem.buffer);
            this._values = [
                // JS values that Go currently has references to, indexed by reference id
                NaN,
                0,
                null,
                true,
                false,
                globalThis,
                this,
            ];
            this._goRefCounts = Array.from({ length: this._values.length }).fill(Infinity); // number of references that Go has to a JS value, indexed by reference id
            this._ids = new Map([
                // mapping from JS values to reference ids
                [0, 1],
                [null, 2],
                [true, 3],
                [false, 4],
                [globalThis, 5],
                [this, 6],
            ]);
            this._idPool = []; // unused ids that have been garbage collected
            this.exited = false; // whether the Go program has exited

            // Pass command line arguments and environment variables to WebAssembly by writing them to the linear memory.
            let offset = 4096;

            const strPtr = (str) => {
                const ptr = offset;
                const bytes = encoder.encode(str + '\0');
                new Uint8Array(this.mem.buffer, offset, bytes.length).set(bytes);
                offset += bytes.length;
                if (offset % 8 !== 0) {
                    offset += 8 - (offset % 8);
                }
                return ptr;
            };

            const argc = this.argv.length;

            const argvPtrs = [];
            for (const arg of this.argv) {
                argvPtrs.push(strPtr(arg));
            }
            argvPtrs.push(0);

            const keys = Object.keys(this.env).toSorted();
            for (const key of keys) {
                argvPtrs.push(strPtr(`${key}=${this.env[key]}`));
            }
            argvPtrs.push(0);

            const argv = offset;
            for (const ptr of argvPtrs) {
                this.mem.setUint32(offset, ptr, true);
                this.mem.setUint32(offset + 4, 0, true);
                offset += 8;
            }

            // The linker guarantees global data starts from at least wasmMinDataAddr.
            // Keep in sync with cmd/link/internal/ld/data.go:wasmMinDataAddr.
            const wasmMinDataAddr = 4096 + 8192;
            if (offset >= wasmMinDataAddr) {
                throw new Error('total length of command line and environment variables exceeds limit');
            }

            this._inst.exports.run(argc, argv);
            if (this.exited) {
                this._resolveExitPromise();
            }
            await this._exitPromise;
        }

        _resume() {
            if (this.exited) {
                throw new Error('Go program has already exited');
            }
            this._inst.exports.resume();
            if (this.exited) {
                this._resolveExitPromise();
            }
        }

        _makeFuncWrapper(id) {
            // somehow avoiding aliasing this with an arrow function doesn't work
            // eslint-disable-next-line unicorn/no-this-assignment, @typescript-eslint/no-this-alias
            const go = this;
            return function () {
                const event = { id, this: this, args: arguments };
                go._pendingEvent = event;
                go._resume();
                return event.result;
            };
        }
    };
})();

export const Go = globalThis.Go;
